Im new to this site and am trying to find some good info from readers on Holley carbs! The problem I am having is at idle tooooo rich! Float level is good air mix screws 1 turn out and still way rich at idle! My combo is 468 BBC 10.1 comp. Brodix BB2 heads and 4500 intake with an adapter for a 4150 carb MSD dizzy and 6AL box! I have tryed 3 different carbs and all are rich at idle 1 is a brand new Chuck Nyutten built 850! Any info. would be helpful Thanks WT :smile20: :huh:
Holley to rich at idle
- Thread starter Widetrack
- Start date
IMPATIENT 1
New member
watcha you doin here coby :huh: :smile15: :smile13:
IMPATIENT 1
New member
coby, if the chuck carb is 1 to 1 linkage, you have to adjust the rear at the same time as the frt, idle screws and idle mixture screws. if you adjust the frt idle screw without touching the rear, the frt barrels will be slobbery and make the motor run rich. does it have air bleeds? is it 1 to 1 or progressive linkage?
IMPATIENT 1 said:
This carb operates on the front two till the linkage on the right side of the carb startes to open the rear. Just by working with the screws on all 4 corners I end up with the fronts way open and the back close to closed off! Didn't want to get the balance off that much and went back to 1 1/2 turns out all 4! Idles good, blip the pedel hard and and it revs good comes back to idle without stumbling just fuel smoke! And your eyes :smile21: from the fumes! WT :smile20:
And I had chatted with Cordog a few days ago and he sent me to this site!
what is your timing set at :smile12: :smile12: :smile12: :smile12:
i know most just set the total to whatever 36-38 but have you ever checked your intial just for fun :smile12: :smile12:
have you changed the main jets down any??that has some affect on the holleys at idle been there
what is your fuel pressure??
what is the power vlave size if any???maybe get some more info coby,trying to help,trav :smile15: :smile15: :smile15: :smile15:
i know most just set the total to whatever 36-38 but have you ever checked your intial just for fun :smile12: :smile12:
have you changed the main jets down any??that has some affect on the holleys at idle been there
what is your fuel pressure??
what is the power vlave size if any???maybe get some more info coby,trying to help,trav :smile15: :smile15: :smile15: :smile15:
IMPATIENT 1
New member
so you're just trying to correct the smoking when you get into it? you can work with accelerator pump shooters to get that right, or play with the pump cam, either way. i've never personally adjusted a 4150 carb that liked more than a 1 full turn on each meter plate screw, but i use a vaccum gauge when i set em under the carb.your's has 4 corner idle, so all 4 corners need to be the same distance out, if the frt are 1 turn out, the back should be as well. the mainjets don't come into play much at idle, idle has its own circuits in the carb.Widetrack said:
IMPATIENT 1 said:
i like your advice tom,scott was the one that told me about the main jet thing at idle and he was right on 2 carbs that were being jackasses,what about timing that plays a important part :smile15: :smile15: :smile15: :smile15
ther than that tom you suck :smile23: :smile23: :smile23: :smile23: :smile23:IMPATIENT 1
New member
sure, i can see mainjets causing issues on a dominator or a 4150 with 1 to 1 linkage but not a 4781. at idle, you're pulling fuel from the idle circuits, then as you mash the gas, the shooters spray in fuel, the motor revs up and creates the signal to the boosters, boosters start pulling fuel thru the mainjets and slobbers it in. that's basic carburetor crackalating :smile13: a dominator with a 3rd circuit will inject fuel into the barrel during part throttle just to keep the signal crisp to the boosters(ie, runnin big ass boosters that normally would have a flat spot in the throttle without the 3rd circuit of fuel). i know 4150's pretty well, its the dominators that took me a longtime to figure out how to tune, they're finicky as hell.
Ignition problems often times have the same symptoms as fuel problems. The under load question is where I was curious. A weak spark tends to show itself under load and increased timing. You might try a different coil if you can get your hands on one. Just an idea. But, if it responsive to throttle.. :huh: Good luck.
Thanks! I changed jets and I think I have got it squard off! On the coil I was thinking I might have a problem there. Blaster II laying on its side so I will replace the coil and stand it upright! When I changed the jets starting was a whole lot better and responce was over the top! :smile19: Now its testing time! :smile15: Thanks again guys! WT :smile20:
Coby
Coby
Update! Yes! :smile19: I found the problem, Carbon Tracking :smile18:This has blown my mind for days! That was not all the problem jetting is still a little rich but it is kicking azz :smile19: right now so much better than before! I will have to do some more testing an tuning to get opitum. Might see some more MPH? Thanks guys! WT :smile20:
Coby
Coby
John
New member
i know this is a little late and im no expert by any means but adjusting the jets is not going to have ANY effect on the idle circuit, i know this cause my motor was idling rich and was a little lean on top end, they are independent of each other, at idle the power valve is actually pulling fuel away from the jets with the fuel running through the idle circuit. on the metering plate the idle circuit hole is .119 on what you need to do is choke this hole down to around .050 or so for a boat on a drag car you should go as small as .025 or so.
John I did this and it helped a lot! Next thing was Timing and carbon tracking fixed all problems and it ran great till! :smile14:It lost a head off the no.8 EXT. valve! :smile18: LOL start all over with more motor! Thanks for the info sounds like you have worked with this problem before! Thanks WT :smile20: